As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
VIBRATION STILL FELT ON 6 MINUTE CYCLE. CAN BE FELT IN COCKPIT FLOOR. ALL CRUISE ALTITUDES. FWD CARGO HEAT DUCTING IN RT AC BAY IS SECURED. WILL NEED TO INSPECT PICCOLO DUCT IN FWD CARGO PIT FLOOR. NOT ENOUGH TIME TO DISASSEMBLE FWD CARGO PIT FLOOR PANELS TO ACCESS DUCT. REPLACED THE CONTROL VALVE PER MM. OPS CHECKED OKAY. NO VIBRATION NOTED.